Epithelial-mesenchymal transition classification of circulating tumor cells in lung and colon cancer patients: potential role in clinical practice

BACKGROUND: Tumor cells undergoing epithelial-mesenchymal transition (EMT) display enhanced ability to enter the circulation, thereby being major source of circulating tumor cells (CTCs). In this study, we aimed to better understand the roles of CTC undergoing EMT in monitoring cancer progression. METHODS: We analyzed gene expression profiling of epithelial and mesenchymal markers in lung or colon tumor samples by mining TCGA database. We detected CTCs and classify their EMT phenotypes of 31 patients with lung or colon cancer by using a CanPatrol CTC-enrichment technique. RESULTS: The bioinformatic analysis indicated that mesenchymal markers were expressed in a subset of lung tumor samples, and its high expression was associated with poor survival of lung cancer patients. However, in colon cancer, majority of tumor samples expressed hybrid epithelial/mesenchymal markers. CTC analysis with EMT classification showed that the number of CTCs with mesenchymal phenotype was high in lung cancer patients with the advanced stage. Dynamic CTC analysis in a lung cancer patient indicated that CTC with mesenchymal phenotype was effective to monitor tumor progression. In a colon cancer patient, dynamic CTC analysis indicated that CTC with hybrid epithelial/mesenchymal phenotypes was an effective biomarker to guide therapy. CONCLUSIONS: Encouraging results from this proof-of-concept study show that CTC with mesenchymal phenotype or hybrid epithelial/mesenchymal phenotypes could be a potential biomarker for monitoring tumor progression in lung or colon cancer respectively.